The present disclosure relates to a method and apparatus for allocating resources for an unlicensed band in a system sharing a resource for device-to-device communication.
To satisfy demands for wireless data traffic having increased since commercialization of 4th-Generation (4G) communication systems, efforts have been made to develop improved 5th-Generation (5G) communication systems or pre-5G communication systems. For this reason, the 5G communication system or the pre-5G communication system is also called a beyond-4G-network communication system or a post-Long Term Evolution (LTE) system.
To achieve a high data rate, implementation of the 5G communication system in an ultra-high frequency (mmWave) band (e.g., a 60 GHz band) is under consideration. In the 5G communication system, beamforming, massive multi-input multi-output (MIMO), full dimensional MIMO (FD-MIMO), an array antenna, analog beamforming, and large-scale antenna technologies have been discussed to alleviate a propagation path loss and to increase a propagation distance in the ultra-high frequency band.
For system network improvement, in the 5G communication system, techniques such as an evolved small cell, an advanced small cell, a cloud radio access network (RAN), an ultra-dense network, device to device (D2D) communication, a wireless backhaul, a moving network, cooperative communication, coordinated multi-points (CoMPs), and interference cancellation have been developed.
In the 5G system, advanced coding modulation (ACM) schemes including hybrid frequency-shift keying (FSK) and quadrature amplitude modulation (QAM) modulation (FQAM) and sliding window superposition coding (SWSC), and advanced access schemes including filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) have been developed.
To improve speed and capacity of an LTE network along with development of LTE, improved techniques such as LTE in Unlicensed Spectrum (LTE-U) using a shared band have been studied. LTE-U or Licensed-Assisted Access (LAA) means a technology for integrating a licensed spectrum or licensed band and an unlicensed spectrum or unlicensed band as well as a licensed band used for existing LTE communication, by using carrier aggregation (CA), and uses a stable licensed band as an anchor to process all control signals and signaling, thereby supporting a quality of service (QoS) and smooth mobility. Moreover, LTE-U or LAA secures a wide data pipe based on extension to an unlicensed band, thus providing users with improved mobile broadband experiences.
Since an unlicensed band is a shared band available to any technique or device, most countries have established regulations on the use of an unlicensed band. To reduce interference between devices in an unlicensed band, a transmission power of a device using an unlicensed band may be limited to a lower level than a licensed band.
Transmission regulations for a shared band like a license-exempt band or an unlicensed band provide various types of schemes to alleviate signal interference between devices, such as a scheme of limiting a transmission power to prevent a reception power in a specific distance from being greater than or equal to a particular value, a scheme of hopping a position on a time or frequency resource or allowing use of only some of total resources, a scheme of listening a signal from another device and allowing transmission when a reception power of the signal is less than a particular value, and so forth.
Existing cellular communication such as LTE requires a resource allocation procedure based on channel measurement and link adaptation to adaptively determine a transmission capacity of a transmission/reception link. However, in a shared band, such as an unlicensed band, for which rules for co-existence of different communication systems are established, several problems may occur in application of existing resource allocation schemes. As a result, a need has arisen for a new resource allocation scheme for communication using an unlicensed band.